Bending tool



Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE 1 Claim.

My invention has relation to improvements in bending tools and itconsists in the novel features of construction more fully set forth inthe specification and pointed out in the claim.

The invention is more particularly directed to tools for bendingconnecting rods of internal combustion engines for the purpose ofrestoring the proper alinement of the engine piston and crank shaft.

The principal object of the invention is to provide a bending tool thatmay be applied to the iiston pins holding the piston and connecting rodin assembled relation. A further object of the invention is to provide abending tool that is instantly adjustable for operations on pistons ofvarying sizes. Further objects are to provide a tool for the purposestated that is simple and rigid in construction; one that is easilyoperated; and one possessing further and other advantages betterapparent from a detailed description of the invention in connection withthe accompanying drawing, in which:

Figure l is a side elevation of my improved bending tool shown appliedto an assembled connecting rod and piston for the purpose of restoringthe correct alinement thereof; Fig. 2 is a top plan of my improvedbending tool; Fig. 3 is a top plan of a connecting rod and pistonassembly showing the bending tool applied thereto; and Fig. 4 is a topplan of a modified form of bending tool.

It is a matter of common knowledge among automobile mechanics that forvarious reasons pistons will get out of alinement with the crank shaftwhich serves to actuate the piston. This disalinement may be caused byeither a bent ,or twisted connecting rod, in the first instance causingthe piston to teeter in the cylinder and eventually producing a severepiston slap, and in the second instance effectinga rotation from itsnormal position of the piston in the cylinder so that the thrust thereonwill come in a place at which the piston is not designed to receive saidthrust.

Skilled mechanics readily perceive the above mentioned defects and seekto correct them by removing the connecting rod and straightening thesame by twisting and bending operations applied directly to theconnecting rod. However, after the connecting rod has been straightenedit is not necessarily true that the piston will be prop-- erly alined,which must be determined by the mechanic by trial and retrial. Myimproved bending tool is applied directly to the piston pins holding thepiston and connecting rod in assembled relation so that the bendingoperations on the connecting rod are governed by the degree ofdisalinement of the piston and are performed for the purpose ofrestoring the correct alinement thereof irrespective of whether theconnecting rod is perfectly straight or not. This 5 is as it should bebecause, as. stated above, the purpose of straightening the connectingrod is to restore the alinement of the piston and not merely to have astraight connecting rod.

This comparatively simple and direct operation of my improved bendingtool will be more clearly understood by referring to the drawing, inwhich P represents a piston and R a connecting rod assembled by means ofa piston or wrist pin W. We will assume that the piston P is notproperly lined up with the engine crank shaft, the center line of whichis indicated by CL in Fig. 1. After having determined the direction andthe amount of the disalinement the mechanic clamps the connecting rod Rbetween the jaws J, J of a suitable device preparatory to bending theconnecting rod R with my improved bending tool for the purpose ofrestoring correct piston alinement. The bending tool comprises aU-shaped yoke I, preferably formed of a hollow casting of rectangularcross section, in the walls of the sides 2, 2 of which are openings 0, oin which are slidably mounted bars 3, 3. Each of the bars 3 passesentirely through the side 2 of the yoke in which it is mounted and hasits inner end 4 tapered as shown so as to readily enter the hollow wristpin W. A stop pin 5 is passed through the inner end of each bar 3immediately behind the tapered end 4, and a knurled portion 6 isprovided on the outer end of each bar 3 to facilitate the grippingthereof by the operator. In order to apply the bending tool to theassembled piston P and connecting rod R the operator grasps the knurledportions 6, 6 of the bars 3, 3 and slides the bars outwardly far enoughso that the tapered ends 4, 4 thereof may be inserted into the ends ofthe wrist pin W. If he has previously determined that the disalinementhas caused a rotation of the wrist pin in a ver tical plane (asindicated by the center lines a: and y showing such rotation greatlyexaggerated in Fig. l) he appliesthe necessary amount of force to thebars 3, 3 to rotate the Wrist pin in a direction to correct suchdisalinement. Of course, in this rotating movement the connecting rod Rwill undergo a bending movement. If, on the other hand, the disalinementis due to a twist in the connecting rod R the wrist pin will have beenrotated in a horizontal plane (as indicated in Fig. 3 by the centerlines 2:, y greatly exaggerated) and may be restored to its properposition by a counter rotation by the application of the necessary forceto the bars 3, 3.

From the foregoing it is apparent that by means of my improved bendingtool the connecting rod R may be bent or twisted, or both if necessary,in order to restore correct alinement to the piston P and greateraccuracy may be obtained because the bending force is applied directlyto the piston, the object of the relinement.

In Fig. 4 I show a modification of the bending tool wherein only onebending bar I0 is used. Instead of the oppositely disposed bending barof the main form I secure a tapered stud H into the yoke I2. As in themain form, however, the bar In and stud II are in axial alinement andthe bar I0 is slidably mounted in the yoke I 2 for the purpose ofadjustment.

Having described my invention, I claim:

A connecting rod bending tool comprising a U- shaped yoke, the sides ofsaid yoke having circular openings near their ends in axial alinementwith each other, a pair of bars carried by said yoke in opposingrelation, each bar having bearing in one of said openings and beingslidable therein, each barbeing circular in cross section and tapered atone end to readily enter a hollow wrist pin and having means thereon tolimit sliding movement of the bar in one direction and said bars beingof substantial length to serve as operating handles for the tool.

JOSEPH SUNNEN.

